Over the last 7 years, we’ve seen a fair share of building blunders. Some things are simple issues of quality control and others simply an extra step to make everything come together. Here are 3 ways to ensure a bulletproof bamboo bike.
Oil & resin don’t mix. Wear gloves during all states of your tacking and wrapping process. Before you mix up any resin, spend 5 minutes and wipe all metal surfaces with rubbing alcohol or a degreaser. Degreasers that work on wood should be applied to the bamboo, once for areas that have raw fibers exposed (mitered). 2-3 times for the rest of the bamboo. Wrap (hemp & resin) and seal the bamboo only when the bamboo is degreased. Degrease your metal pieces too (post knurling, see below)!!
Materials: Nitril gloves, wood degreaser or rubbing alcohol, lint free towel or paper
Start with a few rolls of electrical tape. Grab a drill & bore 1/8in holes into the roll (roughly 1/2in apart). Do this before any resin gets poured! The holes in the tape will allow excess resin to leak out & produce a stronger composite.
Once you’ve finished wrapping, start your compaction by anchoring the electrical tape with the sticky side facing up. Follow the load lines of the hemp fibers as you wrap the electrical tape around the soft composite below. Make sure your tape is kept wide (flat against lug) at all times, any twists in the tape will create divots in your dried composite. After you’ve compacted most of the lug with tape, wipe away any excess resin with your glove. Feel around your lug & note any soft spots. Finish off with a few tight wraps with the electrical tape, making sure to pull tightly over soft spots.
Knurling is a manufacturing process where a criss-cross (repeating diamond) pattern is rolled onto metal. Most of our kits are pre-knurled already, but for those who are swapping in custom parts follow the directions below:
Delamination - don’t let it happen. The biggest problem along aggressive riders (high torque between bottom bracket shell & lug) is delamination. If you think a 60grit sandpaper on metal will do it bonding justice under repeated skidding and pounding uphill, think again. If you have access to lathe and knurling vise, do it. For the home builder this can replicate with a Dremel and a extra thin cut off blade. The idea here is to produce physical grooves in the metal where the fiber can cling onto, essentially providing a toothed surface where the composite & metal interlock. Think Wolverine. Gash interlocking XXXX into your metal parts (all areas to be wrapped over). Don’t cut too deep or simply brush the surface. Roughly 1mm deep gashes will suffice.